The present invention relates to an ink-jet printer for printing an image on a print medium held on a rotary drum with ink ejected from a print head, and more particularly to an ink-jet printer in which a print head is fixed between a pair of head supporting frames which face each other in an axial direction of the rotary drum.
For example, Jpn. Pat. Appln. KOKAI Publication No. 10-138520 discloses a drum rotation ink-jet printer which can make a large number of prints in a short period of time. The drum rotation ink-jet printer comprises a rotary drum which rotates in one direction and a head unit for printing an image on a paper sheet wound around the rotary drum and rotating along with the drum. The head unit has a plurality of ink-jet nozzles arranged in the axial direction of the Rotary drum to extend across the paper sheet, and ejects ink from the ink-jet nozzles onto the paper sheet, which is moved relative to the head unit by rotation of the rotary drum. Since this structure does not require remarkable movement of the head unit as in the conventional serial ink-jet printer, printing can be performed at a high speed. Further, since ink is supplied to the head unit from an ink tank of a large capacity located apart from the head unit, the number of sheets printed for each supplementation of ink can be increased.
The ink-jet printer of this type requires periodic maintenance to prevent clogging by means of ejecting a predetermined amount of ink through all ink-jet nozzles. In the maintenance, the head unit is moved up by an elevator mechanism to a maintenance position from a print position which is close to the rotary drum. Further, a washing board is inserted between the head unit and the rotary drum to collect the ink ejected from the ink-jet nozzles and to discharge it as waste ink.
The elevator mechanism has first and second head supporting frames which face each other in the axial direction of the rotary drum in order to support both ends of the head unit. The head unit is fixed to the first and second head supporting frames by two screws which are screwed from both sides.
However, when the head unit is fixed by screws from both sides, a great deal of time and labor is required for attaching or detaching the head unit to or from the ink-jet printer in the case of assembly, inspection, repair, or replacement of printer components. Further, not only the aforementioned screwing structure is required, but also a workspace must be reserved in the printer to fasten the screws. The workspace is located outside the first and second head supporting frames in the axial direction of the rotary drum. This inevitably increases the printer width, which considerably depends on the length of the head unit extending in the axial direction of the rotary drum and has less degree of freedom as compared to the depth. Consequently, it is difficult to reduce the size and weight of the printers to realize a widespread use thereof.
An object of the present invention is to provide an ink-jet printer in which quick and easy attachment or detachment of a head unit can be achieved without requiring an increase in width of the printer.
According to the present invention, there is provided an ink-jet printer which comprises a medium carrier for carrying a print medium; a head unit, having a plurality of ink-jet nozzles arranged in a width direction of the medium carrier, for ejecting ink toward the print medium carried by the rotary drum from the ink-jet nozzles to print an image on the print medium; and a head supporting mechanism for supporting the head unit detachably attached thereto; wherein the supporting mechanism includes first and second supporting frames facing each other in the width direction of the medium carrier; first and second supporting sections, respectively protruded from the first and the second supporting frames, for receiving first and second ends of the head unit put thereon and supporting the head unit so as to be slidable in the width direction of the rotary drum; an urging member for urging the first end of the head unit received by the first supporting section toward the second supporting frame while allowing vertical movement of the first end to and from the first supporting section; and a position adjusting member for sliding the second end of the head unit put on the second supporting section toward the first supporting frame against urging force from the urging member.
In this ink-jet printer, the head unit can be quickly and easily attached to and detached from the head supporting mechanism. At this time, it is only necessary for the operator to hold the head unit by hand and move it vertically. Further, since the head unit is slid by the urging force from the urging member after attachment to the head supporting mechanism, the position of the head unit can be automatically determined in the width direction of the medium carrier.
Moreover, this position is also adjustable by the position adjusting member. With the structure described above, the width of the ink-jet printer is prevented from increasing, while the size, weight and cost of the ink-jet printer can be reduced. Since the workspace is located only on one side of the ink-jet printer, positional adjustment of the head unit can be performed quickly and easily without being considerably influenced by the installation space of the printer, as compared with the case where both sides of the printer are occupied.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.